Enhancing the antimicrobial activity of ginseng against Bacillus cereus and Staphylococcus aureus by heat treatment.

This study evaluated the antimicrobial activities [diffusion inhibition zone, minimum inhibitory concentration (MIC), and minimum bactericidal concentration], of heated ginseng extracts (ethanol and methanol). The extract yields, ginsenoside compositions, growth inhibitory effects against Bacillus cereus and Staphylococcus aureus and bacterial cell membrane potential changes, were also investigated. Methanol extracts of heated ginseng, showed higher antimicrobial activity than ethanol extracts. B. cereus was more easily inhibited than S. aureus. Ginseng heated at 100 °C for 2 and 16 h, showed maximum antimicrobial activity against B. cereus and S. aureus, respectively. In the growth inhibitory test, S. aureus and B. cereus were completely inhibited after 2 and 8 h culture at the MIC. The cell membrane potential decreased with increasing concentration of extract, indicating cell metabolism disruption. Ginsenosides Rg3, a potent antibacterial substance, which were absent in non-heated ginseng, were produced by heating ginseng at 100 °C for 4 and 8 h, respectively.

Shelf life extension of Pacific white shrimp (Litopenaeus vannamei) using chitosan and ε-polylysine during cold storage.

In this study, we examined the effects of an ε-polylysine (PL) and chitosan (CH) coating on the quality of shrimp under refrigeration. Pacific white shrimp (Litopenaeus vannamei) were coated with PL, CH, or CH + PL and stored at 4 °C for 15 days. The quality of shrimp was measured by observing changes in microbiota, pH, total volatile basic nitrogen (TVB-N), and sensory characteristics. Among the coating films, the CH + PL coating most effectively inhibited the growth of mesophilic and psychrotrophic bacteria, Pseudomonas spp., and H2S-producing bacteria. This coating increased the shelf life of shrimp by decreasing the amount of mesophilic and psychrotrophic bacteria, with inhibition greater than three log cycles on the ninth day of storage. In addition, the CH and CH + PL coatings effectively suppressed the formation of TVB-N compared with that in the control by 43% and 30%, respectively. The pH of all treated samples increased slowly compared with that of the control, but no significant difference was observed. Sensory quality was similar to microbial and physicochemical properties, and the acceptability of all treated samples gradually decreased.

Characterization of silver nanoparticle aggregates using single particle-inductively coupled plasma-mass spectrometry (spICP-MS).

The single particle-inductively coupled plasma-mass spectrometry was applied to characterize the aggregates of AgNPs. was applied to characterize the aggregates of AgNPs. Two sizes of citrate-AgNPs and PVP-AgNPs were used at relatively high and predicted environmental concentrations under various ionic strengths. Citrate-AgNP aggregated with increases in the ionic strength, whereas PVP-AgNPs were sterically stable. The critical coagulation concentrations were 85 mM and 100 mM NaNO3 for 60 nm and 100 nm citrate-AgNPs at 2 mg L-1 as total Ag obtained by dynamic light scattering (DLS). At 2 mg L-1 as total Ag, the mass of an aggregate gradually increased with increasing ionic strength for both citrate-AgNP during spICP-MS analyses. The average number of single particles derived from the mass in an aggregate was calculated to be 8.68 and 5.95 for 60 nm and 100 nm citrate-AgNPs at 85 mM and 100 mM NaNO3, respectively after 2 h. The mass fractal dimensions were determined to be 2.97 and 2.83, further implying that the aggregate structures were very rigid and compact. Only marginal increases in the average mass and number of single particles in the aggregate units were found during 24 h under environmentally relevant AgNP concentrations. The average number of single particles constituting an aggregate unit for 60 nm and 100 nm citrate-AgNPs was 1.24 and 1.37 after 24 h at a high ionic strength. These results indicate that under environmentally relevant conditions, the collision frequency is predominant in the aggregation and that NPs are likely to encounter natural colloids such as clay and organic matter to form hetero-aggregates.

N-nitrosodimethylamine (NDMA) formation during ozonation of N,N-dimethylhydrazine compounds: Reaction kinetics, mechanisms, and implications for NDMA formation control.

Compounds with N,N-dimethylhydrazine moieties ((CH3)2N-N-) form N-nitrosodimethylamine (NDMA) during ozonation, but the relevant reaction chemistry is hitherto poorly understood. This study investigated the reaction kinetics and mechanisms of NDMA formation during ozonation of unsymmetrical dimethylhydrazine (UDMH) and daminozide (DMZ) as structural model N,N-dimethylhydrazine compounds. The reaction of ozone with these NDMA precursor compounds was fast, and kO3 at pH 7 was 2 × 106 M-1 s-1 for UDMH and 5 × 105 M-1 s-1 for DMZ. Molar NDMA yields (i.e., Δ[NDMA]/Δ[precursor] × 100) were 84% and 100% for UDMH and DMZ, respectively, determined at molar ozone dose ratio ([O3]0/[precursor]0) of ≥4 in the presence of tert-butanol as hydroxyl radical (OH) scavenger. The molar NDMA yields decreased significantly in the absence of tert-butanol, indicating OH formation and its subsequent reaction with the parent precursors forming negligible NDMA. The kOH at pH 7 was 4.9 × 109 M-1 s-1 and 3.4 × 109 M-1 s-1 for UDMH and DMZ, respectively. Reaction mechanisms are proposed in which an ozone adduct is formed at the nitrogen next to N,N-dimethylamine which decomposes via homolytic and heterolytic cleavages of the -N+-O-O-O- bond, forming NDMA as a final product. The heterolytic cleavage pathway explains the significant OH formation via radical intermediates. Overall, significant NDMA formation was found to be unavoidable during ozonation or even O3/H2O2 treatment of waters containing N,N-dimethylhydrazine compounds due to their rapid reaction with ozone forming NDMA with high yield. Thus, source control or pre-treatment of N,N-dimethylhydrazine precursors and post-treatment of NDMA are proposed as the mitigation options.

Transformation of ranitidine during water chlorination and ozonation: Moiety-specific reaction kinetics and elimination efficiency of NDMA formation potential.

Ranitidine can produce high yields of N-nitrosodimethylamine (NDMA) upon chloramination and its presence in water resources is a concern for water utilities using chloramine disinfection. This study assessed the efficiency of water chlorination and ozonation in transforming ranitidine and eliminating its NDMA formation potential (NDMA-FP) by determining moiety-specific reaction kinetics, stoichiometric factors, and elimination levels in real water matrices. Despite the fact that chlorine reacts rapidly with the acetamidine and thioether moieties of ranitidine (k>10(8)M(-1)s(-1) at pH 7), the NDMA-FP decreases significantly only when chlorine reacts with the less reactive tertiary amine (k=3×10(3)M(-1)s(-1) at pH 7) or furan moiety (k=81M(-1)s(-1) at pH 7). Ozone reacts rapidly with all four moieties of ranitidine (k=1.5×10(5)-1.6×10(6)M(-1)s(-1) at pH 7) and its reaction with the tertiary amine or furan moiety leads to complete elimination of the NDMA-FP. Treatments of ranitidine-spiked real water samples have shown that ozonation can efficiently deactivate ranitidine in water and wastewater treatment, while chlorination can be efficient for water containing low concentration of ammonia. This result can be applied to the other structurally similar, potent NDMA precursors.

Analysis of Colonization and Genotyping of the Exotoxins of Staphylococcus aureus in Patients with Atopic Dermatitis.

BACKGROUND: The skin of atopic dermatitis (AD) patients has a high susceptibility to Staphylococcus aureus colonization, and the toxins produced by S. aureus may aggravate AD by acting as superantigens. OBJECTIVE: The purpose of this study was to evaluate the relationship of the skin barrier function, colonization of S. aureus, and the clinical severity of AD. We also examined the predominant toxin genes produced in Korean AD patients. METHODS: Thirty-nine patients with AD were evaluated for clinical severity and skin barrier function by using Severity Scoring of Atopic Dermatitis (SCORAD) index and transepidermal water loss (TEWL). S. aureus was isolated from the forearm, popliteal fossa, and anterior nares of AD patients (n=39) and age-matched controls (n=40); the toxin genes were analyzed by performing multiplex polymerase chain reaction. RESULTS: TEWL showed a statistically significant correlation with clinical severity in patients with AD (p<0.05). TEWL was correlated with the number of S. aureus colonization sites and the presence of nasal colonization, but these results were not statistically significant. S. aureus strains were isolated in 64.1% of the 39 AD patients. The SCORAD index and AD severity were strongly correlated with the number of colonization sites. The predominant toxin gene found in AD patients was staphylococcal enterotoxin a (sea) only, which was produced in 52.6% of patients. The toxin genes sea and toxic shock syndrome toxin-1 (tsst-1) were found together in 42.1%, while tsst-1 only was found in 5.3% of the patients. CONCLUSION: S. aureus strains were isolated in 64.1% of the 39 AD patients. Skin barrier function, as measured by TEWL, revealed a statistically significant correlation with clinical severity in AD patients. The SCORAD index and severity of AD was strongly correlated with the number of colonization. The most common toxin gene was sea in the Korean AD patients and this gene might have an important role in the pathogenesis of AD.

Eccrine angiomatous hamartoma mimicking a traumatic hemorrhage.

Eccrine angiomatous hamartoma (EAH) is a rare benign disease that is characterized by an abnormal proliferation of eccrine glands and vascular elements. It is generally congenital, but it can appear before puberty. It usually presents as a single plaque or nodule, but multiple patch-like lesions are also possible. EAH is mostly asymptomatic, but it is sometimes associated with pain or hyperhidrosis. It generally does not require aggressive treatment, but the lesion can be excised due to pain, enlargement and cosmetic reasons. A 3-week-old Korean female presented with a hemorrhagic skin lesion on the right foot since birth. There was no specific birth history. The lesion first appeared on the third toe of the right foot and quickly spread to almost half of the right foot. Histopathology examination revealed acanthosis in the epidermis and a proliferation of eccrine ducts, glands and capillaries. The eccrine glands were immunohistochemically-positive for carcinoembryonic antigen.

Chromoblastomycosis Caused by Phialophora richardsiae.

Chromoblastomycosis is a chronic fungal disease of the skin and subcutaneous tissues caused by a group of dematiaceous (black) fungi. The most common etiologic agents are Fonsecaea pedrosoi and Cladophialophora carrionii, both of which can be isolated from plant debris. The infection usually follows traumatic inoculation by a penetrating thorn or splinter wound. Several months after the injury, painless papules or nodules appear on the affected area; these papules then progress to scaly and verrucose plaques. We report a case of chromoblastomycosis caused by Phialophora richardsiae, which has been rarely associated with chromoblastomycosis. The case involved a 43-year-old male, who for the past 2 months had noted an erythematous, pustulous plaque that was somewhat dark brown in color on his right shin; the plaque also had intermittent purulent discharge and crust formation. On histopathological examination, chronic granulomatous inflammation and sclerotic cells were seen. The tissue fungus culture grew out the typical black fungi of P. richardsiae, which was confirmed by polymerase chain reaction. The patient has been treated with a combination of terbinafine and itraconazole for 3 months with a good clinical response.